Researchers create stable hybrid laser by 3D printing micro-optics onto fibers

For the primary time, researchers have proven that 3D-printed polymer-based micro-optics can stand up to the warmth and energy ranges that happen inside a laser. The advance permits cheap, compact, and secure laser sources that will be helpful in a wide range of purposes, together with the lidar methods used for autonomous autos.

“We considerably lowered the dimensions of a laser through the use of 3D printing to manufacture high-quality micro-optics immediately on glass fibers used inside lasers,” mentioned analysis group chief Simon Angstenberger from the 4th Physics Institute on the College of Stuttgart in Germany. “That is the primary implementation of such 3D-printed optics in a real-world laser, highlighting their excessive harm threshold and stability.”

Within the journal Optics Letters, the researchers describe how they 3D printed microscale optics immediately onto optical fibers to mix fibers and laser crystals inside a single laser oscillator in a compact approach. The ensuing hybrid laser exhibited secure operation at output powers of over 20 mW at 1063.4 nm and had a most output energy of 37 mW.

The brand new laser combines the compactness, robustness, and low value of fiber-based lasers with the benefits of crystal-based solid-state lasers, which might have a broad vary of properties akin to completely different powers and colours.

“Till now, 3D-printed optics have primarily been used for low-power purposes akin to endoscopy,” mentioned Angstenberger. “The flexibility to make use of them with high-power purposes might be helpful for lithography and laser marking, for instance. We confirmed that these 3D micro-optics printed onto fibers can be utilized to focus giant quantities of sunshine all the way down to a single level, which might be helpful for medical purposes akin to exactly destroying cancerous tissue.”

Taking the warmth

The 4th Physics Institute on the College of Stuttgart has an extended historical past of growing 3D-printed micro-optics, particularly the flexibility to print them immediately on fibers. They use a 3D printing strategy referred to as two-photon polymerization, which focuses an infrared laser right into a UV-sensitive photoresist.

Within the laser’s focal area, two infrared photons might be absorbed concurrently, which hardens the UV resistance. Transferring the main target round permits numerous shapes to be created with excessive precision. This technique use can be utilized to create miniaturized optics and likewise permits novel functionalities such because the creation of free-form optics or advanced lens methods.

“As a result of these 3D-printed components are fabricated from polymers, it was unclear whether or not they might stand up to the numerous quantity of warmth load and optical energy that happens inside a laser cavity,” mentioned Angstenberger. “We discovered that they’re surprisingly secure, and we weren’t capable of observe any form of harm on the lenses even after a number of hours of operating the laser.”

For the brand new examine, the researchers used a 3D printer made by Nanoscribe to manufacture lenses with a 0.25 mm diameter and top of 80 microns onto the tip of a fiber with the identical diameter utilizing two-photon polymerization.

This concerned designing an optical aspect with industrial software program, inserting the fiber into the 3D printer, after which printing the small construction on the tip of the fiber. This course of have to be extraordinarily exact by way of aligning the printing to the fiber and the accuracy of the printing itself.

Making a hybrid laser

After the printing was full, the researchers assembled the laser and the laser cavity. Moderately than utilizing a crystal inside a laser cavity fabricated from cumbersome and expensive mirrors, they used fibers to type a part of the cavity, making a hybrid fiber-crystal laser. The lenses printed on the finish of the fibers focus and accumulate—or couple—the sunshine into and out of the laser crystal.

They then glued the fibers right into a mount to make the laser system extra secure and fewer vulnerable to air turbulence. The crystal and the printed lenses measured simply 5 X 5 cm².

Constantly recording the laser energy over a number of hours verified that the printed optics contained in the system didn’t deteriorate or have an effect on the long-term properties of the laser. Moreover, scanning electron microscopy photos of the optics after use within the laser cavity didn’t present any seen harm. “Curiously, we discovered that the printed optics had been extra secure than the industrial fiber Bragg grating we used, which ended up limiting our most energy,” mentioned Angstenberger.

The researchers at the moment are working to optimize the effectivity of the printed optics. Bigger fibers with optimized freeform and aspherical lens designs or a mixture of lenses printed immediately onto the fiber might assist enhance the output energy. They’d additionally prefer to show completely different crystals within the laser, which might permit the output to be personalized for particular purposes.